The NIST quantum communications group has demonstrated an approach to measure the higher order (second-, third- and fourth) temporal correlations of photons in the near infrared (NIR) region using up-conversion detectors. The NIR photons are up-converted to the visible region and their temporal correlations are then measured using silicon photodiodes. The experimental results reveal that the photon statistics are well preserved in the frequency up-conversion process.

The NIST quantum communications group has demonstrated an approach to measure the higher order (second-, third- and fourth) temporal correlations of photons in the near infrared (NIR) region using an up-conversion device. In the experiment, the team up-converted the NIR photons to the visible region and then perform the temporal correlation measurements using silicon photodiodes. The experimental results reveal that the temporal correlations of the up-converted photons in the visible region agree very well with theoretical predictions. In other words, the photon statistics are well preserved in the frequency up-conversion process.

Two kinds of photons sources are used for this study, a coherent source and a pseudo-thermal source near 1310 nm (NIR). After frequency up-conversion, second-, third- and fourth-order temporal correlations are measured from the up-converted photons at 710 nm (visible).The experimental results reveal that the temporal correlations of the up-converted photons agree very well with theoretical predictions. We conclude that the photon statistics are well-preserved in the up-conversion process.Thus, frequency up-conversion is shown to be an accurate, relatively inexpensive, and highly efficient measurement method for temporal correlation of photons in the NIR region. We further studied the noise from the up-conversion process and its influence on the temporal correlation values. This work is in collaboration with the Center for Nano Science and Technology (CNST), and Physics Laboratory at NIST. The results were published in Optics Express and include an animation showing the fourth order coloration.